The first of the above named parasites is the agent of a disease named mucotaneous leishmaniasis; the second parasite is the agent of visceral leishmaniasis or Kala-azar. Human leishmaniasis are caused by at least 13 different species and subspecies of parasite of the genus Leishmania. The parasites are transmitted to man from other infected human beings or infected vertebrates by sandflies when while the sandflies are taking a blood meal. Leishmaniasis has been reported from about 80 countries and probably some 400,000 new cases occur each year. Recently, the World Health Organization reported 200 million people affected by the disease.
Visceral leishmaniasis is usually fatal if untreated and mucocutaneous leishmaniasis of the New World produces multilation by destruction of the naso-oro-pharyngeal cavity and in some cases death. Since control of the zoonosis of the New World is quite difficult, the only approach to prevent lesions is early diagnosis and radical treatment of patients since drugs are rather unsatisfactory at the present time.
Various types of vaccines have used:
(1) live parasites (Berverian, 1939, Trans. R. Soc. Trop. Med. Hyg. 33: 87-94; Koufman et al., 1978, Isr. Med. Sci. 14:218-222); PA1 (2) frozen promastigotes from culture (Witztum et al., 1979, Isr. J. Med. Sci. 15: 749-73); PA1 (3) sonicated promastigotes (Beacham et al., 1982, Am. J. Trop. Med. Hyg. 31: 252-258); PA1 (4) gamma-irradiated live promastigotes (Howard et al., 1982, J. Immunol. 129: 2206-2212); PA1 (5) formalin-killed promastigotes treated with glucan (Holbrook et al., 1981, Am., J. Trop. Med. Hyg. 30: 762-768).
However, none of the above vaccines have given satifactory results. Only the first and second ones have been applied to human. Since the parasites are alive, the immunity is the consequence of an infection and not the result of vaccination with non-infective parasites.